Production of tsv interconnection structures made up of an insulating contour and a conductive zone situated in the contour and disconnected from the contour

ABSTRACT

A method for producing an interconnection structure is disclosed. In one aspect, there is formation in a substrate of at least one trench forming a closed contour and at least one hole situated inside the closed contour, the trench and the hole being separated by a zone of the substrate. Furthermore, the trench is filled with a dielectric material and the hole is filled with a conducting material.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of French Patent Application No.0958999 filed on Dec. 15, 2009, the contents of which are incorporatedherein by reference in their entirety.

DESCRIPTION

1. Technical Field

The invention concerns the field of microelectronics and microsystems,and in particular that of via interconnection structures, in particularof the Through Silicon Via (TSV) type.

It provides for the implementation of an improved interconnectionstructure.

2. Background of the Invention

In the context of the production of stacks of microelectronic chips, itis known to make TSV (Through Silicon Via) interconnection members, i.e.connection members passing through a substrate to form a connection withone or several chips stacked on that substrate.

These connection elements, also called “vias”, are traditionally made upof an internal conductive portion ensuring the passage of the currentthrough the substrate and connecting device situated on either side ofthe substrate, and an insulating external portion, coating the internalconductive portion, and ensuring that the via is insulated relative tothe semiconducting substrate and other surrounding vias, formed in thesubstrate.

The main steps for manufacturing this type of via are:

-   -   forming a hole in a substrate,    -   producing an insulating thickness on the walls of the hole,    -   filling the hole through deposition of a conductive material,        for example such as doped polysilicon, tungsten, or copper.

Through via production poses problems relative to:

-   -   filling the hole due to the shape factor thereof, which is        generally very high;    -   mechanical stresses related to the filling materials used;    -   insufficient insulation or overly high stray capacity depending        on the dielectric insulation used and the thickness of the        dielectric material of the via.

Documents WO 2004/084300 A1 and U.S. Pat. No. 6,815,827 B2 disclosemethods for producing through vias formed in conducting orsemi-conducting substrates by insulating part of the substrate using atrench forming a closed and insulating contour, the conduction occurringthrough an insulated semi-conducting region of the substrate.

Document US 2009/0181494 A1 provides for an interconnection structure inthe form of a square metal stud insulated by a square contour filledwith dielectric material.

Patent US 2009/0032951 A1 discloses a method for producing an annularvia passing through an insulating zone formed around it.

The problem arises of finding a new method for producing viainterconnection structures passing through a substrate.

BRIEF DESCRIPTION OF THE INVENTION

The present invention first concerns a method for producing aninterconnection structure comprising: the formation, in a substrate, ofat least a first opening, such as at least one trench, forming a closedcontour and at least one second opening, for example in the form of atleast one hole, situated inside said closed contour, the first openingand the second opening being separated by a zone of the substrate, themethod also comprising steps for filling the first opening with adielectric material and the second opening with a conducting material.

The present invention concerns also a method for producing aninterconnection structure comprising: the formation, in a substrate, ofat least a first opening, such as at least one trench, forming a closedcontour and at least one second opening, for example in the form of atleast one hole, situated inside said closed contour, the first openingand the second opening being separated by a zone of the substrate, themethod also comprising steps for filling the first and the secondopenings with a dielectric material or a conducting material, thewithdrawal of this material in one of the openings, the filling of thisopening by the other material.

The first opening and the second opening are formed simultaneously.

Forming an insulating zone that is disconnected from the conduction zonemakes it possible to achieve good quality insulation and limit thecapacitive effect. This advantage can be determining when such astructure is for example produced for RF circuits.

With such a method, it is possible to easily dimension the zone betweenthe first opening and the second opening and to form, with that zone, aguard zone for restoring contact.

According to one possible embodiment, after the formation of the firstopening and the second opening:

-   -   said dielectric material can be deposited in the first and        second openings;    -   the dielectric material is removed from the second opening,    -   the conducting material is formed in the second opening.

According to another possible embodiment after the first and secondopenings are formed, one can:

-   -   form conducting material in the first opening and the second        opening,    -   remove the conducting material from the first opening,    -   deposit the dielectric material in the first opening.

The method can also comprise, between the removal of the dielectricmaterial from the second opening and the formation of the conductingmaterial in the second opening, a step for enlarging the second opening.

This enlargement step can be done so as to form a second, taperedopening.

Openings provided with such a shape can be filled more easily.

The conducting material can be formed in the second opening so as tocover the bottom and walls of the second opening, the method alsocomprising a step consisting of at least partially filling in the secondopening with an insulating material.

According to one possible implementation, the step consisting of fillingin the rest of the second opening with an insulating material can bedone during said step for depositing said dielectric material in thefirst opening, said insulating material making it possible to at leastpartially fill in the second opening being said dielectric material.

The substrate can have a base of a conducting or semi-conductingmaterial.

Said conducting filling material can be a given metal material, afterdeposition of the conducting material in the first opening and thesecond opening, then removal of the conducting material from the firstopening, a heat treatment can be done so as to form an alloy of thegiven semi-conducting material and the given metal material, such as asilicide.

The second opening filled with conducting material forms a conductormember. The method can also comprise: the production of at least oneconnecting stud on said conductor member.

The method can also comprise a step for thinning the substrate so as toreveal an end of said conductor member.

According to one possibility, a conductor stud can be formed on said endof said conductor member.

The substrate can comprise one or several conducting zones situated onone of its faces, said formation of the hole being done by etching fromthe other of its faces so as to reveal at least one of said conductingzones.

The formation of the first and second openings can also comprise theformation of one or several other openings situated inside said closedcontour.

The formation of the first and second openings can also comprise theformation of at least one other opening forming another closed contoursurrounding said closed contour.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood upon reading thedescription of embodiments, provided solely for information andnon-limitingly, in reference to the appended drawings, in which:

FIGS. 1A-1I illustrate different examples of interconnection structuresaccording to the conventional art;

FIGS. 2A-2F illustrate a first embodiment of the production methodaccording to the invention of a TSV interconnection structure;

FIGS. 3A-3D illustrate a second embodiment of a production methodaccording to the invention of a TSV interconnection structure;

FIGS. 4A-4B illustrate another embodiment of a production methodaccording to the invention of a TSV interconnection structure;

FIGS. 5A-5D illustrate a fourth example of an embodiment of a productionmethod according to the invention of a TSV interconnection structure;

FIGS. 6A-6E illustrate a fifth embodiment according to the invention ofa production method of a TSV interconnection structure.

Identical, similar or equivalent parts of the different figures bear thesame numerical references so as to facilitate the transition from onefigure to the next.

The different parts illustrated in the figures are not necessarily shownusing a uniform scale, to make the figures more legible.

DETAILED DESCRIPTION OF THE INVENTION

Examples of TSV interconnection structures, produced using a methodaccording to the invention, are shown in FIGS. 1A-1I.

These structures comprise at least one conductor member passing throughat least part of the thickness of a substrate and at least oneinsulating zone making it possible to insulate the conductor member fromone or several other interconnection structures and the rest of thesubstrate.

FIG. 1A illustrates a first example of an interconnection structure (ina top view) formed in a substrate and comprising a zone 130 with a baseof a dielectric material, for example such as SiO₂, and forming acircular closed contour C1, as well as a conductor member 120 inside thefirst contour C1, the conductor member 120 being able to be metal-based,for example copper, and forming another circular contour C2.

In the example of FIG. 1B, the dielectric zone 130 forms a rectangularcontour C10, while the conductor member 120 also forms a rectangularcontour C20 that is disconnected from and situated inside of the contourC10.

A third example of a structure is provided in FIG. 1C. In that example,the dielectric zone 130 assumes the form of a circular contour C1 insidewhich a plurality of distinct conductor members 120 are found.

The conductor members 120 are cylindrical in this example.

A fourth example of a structure differs from the preceding one in thatthe conductor members assume the shape of a rectangular rhomb (FIG. 1D).

Another example of an interconnection structure comprises a dielectricmaterial zone 130 in the form of a ring and a conductor member 120 inthe form of a cylindrical stud inside said ring (FIG. 1E).

A sixth example of a structure is provided in FIG. 1F, the dielectriczone 130 being in the form of a circular contour C1, while the conductormember 120 is in the form of a plurality of conducting rings connectedto each other via conducting zones joining the rings.

A seventh example of a structure is provided in FIG. 1G, the dielectriczone 130 being in the form of a circular contour, whereas the conductormember 120 is in the form of a spiral.

Another example of a structure is provided in FIG. 1H, the dielectriczone 130 being in the form of a circular contour, whereas the conductormember is in the form of a grate or mesh.

A ninth example of an interconnection structure is provided in FIG. 1I.In this example, the insulating zone 130 forms a first circular contour,whereas a conductor member 120 is situated inside the first circularcontour. Another conductor member 122 forms another circular contourinside which the insulating zone 130 and the conductor member 120 arearranged.

Another dielectric zone 132 in the form of another circular contoursurrounds the conductor members 120, 122 and the insulating zone 130.

In each of the examples of structures provided, an insulating zone and aconductor member surrounded by said zone pass through at least part ofthe thickness of the substrate and are separated from each other by atleast one zone of the substrate, which can have a semi-conductingmaterial as its base.

A first example of a method, according to the invention, for producingan interconnection structure, for example of the type previouslydescribed relative to FIG. 1A, will now be provided relative to FIGS.2A-2F.

In this example, the starting material can be a semi-conductingsubstrate 100, for example Si-based, in which one or several trenches103, 105 are formed at the same time, as well as one or several holes102, 104, the trenches 103, 105 and the holes 102, 104 passing throughat least part of the thickness e of the substrate 100.

The holes and the trenches can have a depth between 100 nanometers and 1millimeter, for instance.

To produce the trenches 103, 105 and the holes 102, 104, one can firstdeposit a mask layer 107, which can for example have a base of SiO₂ orSi₃N₄ and a layer of resin 109, in which openings are formed. Then, thesubstrate is etched through these openings (FIG. 2A).

The trenches are formed such that at least one trench 103 forms a closedcontour around a substrate portion 100 and a hole 102, 104.

The holes are formed such that at least one hole 102 forms a closedcontour around a substrate portion 100.

The layer of resin 109 is then removed, then the trenches 103, 105 andthe holes 102, 104 are filled using a dielectric material 111, forexample SiO₂. The filling can be done by deposition, for example of theSACVD (“Sub Atmospheric Pressure Chemical Vapor Deposition”) type (FIG.2B).

Another resin mask 113 is then formed including openings 115 situatedopposite holes 102, 104. The dielectric material 111 is then removedfrom the hole 102, 104, for example by chemical etching using HF or bydry etching, for an oxide-type dielectric, through the openings 115 ofsaid mask 113.

A metal material 117 is then deposited so as to fill in the holes 102,104 (FIG. 2D).

The metal material 117 can be tungsten, for example, which can forinstance be deposited by CDV (“Chemical Vapor Deposition”) or copper,which can for instance be deposited by ECD (Electro-chemicaldeposition).

The metal material 117 extending past the mouth of the holes 102, 104 isthen removed.

This removal can for example be done using CMP (“Chemical MechanicalPolishing”), so as to also remove the dielectric material 111 on themask layer 107 and protruding past the mouth of the trenches 103, 105(FIG. 2E).

Members 120 have thus been produced with a metal base, passing throughpart of the thickness of the substrate 100 and situated inside aninsulating contour formed by a zone 130 also passing through part of thethickness of the substrate 100, the conductor members 120 beingseparated from the insulating zone 130 by a zone of the substrate 100.

Conducting studs 121 are then formed on the front face of the substrate,on the holes 102, 104 filled with metal material 117 so as to be incontact with the conductor members 120.

The substrate 100 can then be thinned through its back face so as toreveal the bottom of the holes 102, 104. Access is thus provided to theconductor members 120.

According to one possibility, to perform the thinning, a handlesubstrate 200 can be attached.

Conducting studs 131 are then formed on the back face of the substrateand in contact with the conducting members 120.

A second embodiment of a method according to the invention for producingan interconnection structure will now be provided relative to FIGS.3A-3D.

Steps can first be carried out as in the example method previouslydescribed relative to FIGS. 2A-2D.

The metal material 117 can then be deposited, so as to cover the bottomand the walls of the holes 102, 104 (FIG. 3A).

The deposited metal material can for example be W, or Ti, or Ni, or Pt,or Co, according to a thickness that may be between 300 and 1000nanometers. The metal material can be deposited with a thicknessprovided such that the holes are not completely filled in.

A step is then carried out to form silicide zones 122 in the holes 102,104, by performing a heat treatment, for example at a temperature in thevicinity of 400° C. to form the Ni silicide.

The silicide formed can for example be one of the following materials:WSi₂, TiSi₂, NiSi, PtSi, CoSi₂ and have a thickness for example between1 and 3 micrometers (FIG. 3B).

Conductor members 122 have thus been formed with a base of a conductingmaterial, passing through part of the thickness of the substrate 100 andsituated inside an insulating contour formed by a zone 130 also passingthrough a portion of the thickness of the substrate 100, the conductormembers 122 being separated from the insulating zone 130 by asemi-conducting zone of the substrate 100.

Conducting studs 121 are then formed on the semi-conducting holes 102,104 filled with metal alloy resulting from the reaction between themetal 117 and semi-conductor material of the substrate 100, so as to bein contact with the conductor members 122 (FIG. 3C).

A thinning of the substrate 100 through its back face and so as toreveal the bottom of the holes 102, 104 can then be done. Access is thusprovided to the conductor members 122.

According to one possibility, to perform the thinning, a handlesubstrate 200 can be attached.

Conducting studs 131 are then formed on the back face of the substrateand in contact with the conducting members 122.

According to one alternative of either of the examples of methods justprovided, before filling the holes 102, 104 with a metal material 117,the holes 102, 104 can be enlarged, for example through isotropicetching thereof through the layers 107 and 111.

The etching can be done so as to form holes 102, 104 having inclinedwalls and a tapered shape. Such a shape of the holes 102, 104 allowseasier filling thereof.

The metal material 117 is then deposited in a uniform thickness at thebottom and on the walls of the holes 102, 104.

The thickness of metal material 117 deposited can be provided such thatafter deposition, the central portion of the holes 102, 104 is notfilled in.

This portion is then filled in using a dielectric material 127 (FIG.4A).

According to one possibility illustrated in FIG. 4B, the central portionof the holes can be filled in using a dielectric material 111 usingwhich the trenches 103, 105 are filled in (FIG. 4B).

Another example of a method for producing an interconnection structureis shown in FIGS. 5A-5D.

Steps can first be performed as previously given relative to FIG. 2A.

Then, the holes 102, 104 and trenches 103, 105 can be filled in using ametal material 117.

The filling may protrude past the mouth of the holes 102, 104 andtrenches 103 (FIG. 5A). The metal protruding from the holes 102, 104 isremoved by CMP.

Another resin mask 114 is then formed including openings 116 situatedopposite trenches 103, 105.

The metal material 117 is removed from the trenches 103, 105, forexample by chemical etching using HF—HNO₃ when the metal material istungsten through the openings 116 of said mask 114 (FIG. 5B). The mask114 is removed using a stripping method.

Then, the trenches 103, 105 are filled in using a dielectric material111.

The filling can be done so as to protrude past the mouth of the holes102, 104 and trenches 103, 105 (FIG. 5C).

Members 120 are thus formed with a base of a metal material, passingthrough part of the thickness of the substrate 100 and situated insidean insulating contour formed by a zone 130 also passing through part ofthe thickness of the substrate 100, the conductor members 117 beingseparated from the insulating zone 130 by a semi-conducting zone of thesubstrate 100.

Openings are then formed in the layer of dielectric material 111, so asto uncover the holes 102, 104.

Then, conducting studs 121 are formed on the metal-based conductormembers 117.

Steps for thinning the substrate 100 so as to uncover the holes 102, 104on the back face of the substrate 100, then for forming conducting studs131 on the back face of the substrate 100 and in contact with theconductor members 117, are then done (FIG. 5D).

A method according to the invention for producing interconnections canbe implemented during “post process” steps, for example in a substrate100, once it has been assembled with a handle substrate 200.

An example of a “post process” method for producing a TSV-type structureis illustrated in FIGS. 6A-6E.

The structure produced can for example assume a similar form to thatdescribed above relative to FIG. 1E.

In this example, the starting structure of the method is formed by asubstrate 100 attached on a handle substrate 200 and possibly thinned.

One or several trenches 103, 105 are first formed, as well as one orseveral holes 302, 304, through a mask 109, the trenches 103, 105 andthe holes 302, 304 passing through the thickness of the substrate 100.

The holes 302, 304 are formed opposite conducting studs 321, so as touncover said studs 321.

The trenches are made such that at least one trench 103 forms a closedcontour around a substrate portion and a hole 302, 304.

The holes 302, 304 are surrounded by the material of the substrate 100(FIG. 6A).

The trenches 103, 105 are then filled in using a dielectric material 111(FIG. 5C).

The filling can be done so as to cover the walls and bottom of the holes302, 304, and to protrude past the mouth of the holes 102, 104 and thetrenches 103, 105 (FIG. 6B).

The dielectric material 111 is then removed from the holes 302, 304, forexample by chemical etching using HF when the dielectric is SiO₂ throughthe openings of a resin mask 314 (FIG. 6C). Then, after having removedthe resin mask 314, the holes 302, 304 are filled in using a metalmaterial 117 (FIG. 6D).

The filling can have been done so as to protrude past the mouth of theholes 302, 304 and the trenches 103, 105. In that case, the excess metalmaterial 117 protruding from the holes 302, 304 is removed, for exampleby CMP polishing.

Conductor members 120 have thus been formed in contact with theconnection studs 321. Then, other conducting studs 331 are formed, incontact with the conductor members 120 on the face of the substrate 100opposite that on which the connecting studs 321 are arranged (FIG. 6E).

It will be understood that other aspects will become readily apparent tothose skilled in the art from the descriptions herein. One skilled inthe art would understand that the present disclosure, the drawings andthe descriptions in the present disclosure are to be regarded asillustrative in nature and not as restrictive.

The description set forth in connection with the appended drawings isintended as a description of various aspects of the present disclosureand is not intended to represent the only aspects in which the presentdisclosure may be practiced. Each aspect described in this disclosure isprovided merely as an example or illustration of the present disclosure,and should not necessarily be construed as preferred or advantageousover other aspects. The description includes specific details for thepurpose of providing a thorough understanding of the present disclosure.However, it will be apparent to those skilled in the art that thepresent disclosure may be practiced without these specific details.

The description of the disclosed aspects is provided to enable anyperson skilled in the art to make or use the present disclosure. Variousmodifications to these aspects will be readily apparent to those skilledin the art, and the generic principles defined herein may be applied toother aspects without departing from the spirit or scope of thedisclosure.

1. A method for producing an interconnection structure with at least onevia passing through a substrate, the method comprising: simultaneouslyforming, in the substrate, at least one first opening producing a closedcontour and at least one second opening situated inside the closedcontour, the first opening and the second opening being separated by azone of the substrate, the method further comprising filling the firstand second opening with a dielectric material; removing the dielectricmaterial in the second opening; and forming or depositing a conductingmaterial in the second opening.
 2. The method according to claim 1, thesecond opening not passing through the substrate, after being filledwith the conducting material, the method further comprising revealingthe second opening to form one interconnection via.
 3. The methodaccording to claim 1, wherein the conducting material is formed in thesecond opening so as to cover the bottom and the walls of the secondopening, the method further comprising filling in the rest of the secondopening with an insulating material.
 4. The method for producing aninterconnection structure according to claim 1, further comprising,enlarging the second opening prior to the removal of the dielectricmaterial from the second opening and following depositing or forming theconducting material in the second opening.
 5. The method for producingan interconnection structure according to claim 1, wherein the substratehas a base of a given conducting or semi-conducting material and theconducting material is a metal.
 6. The method for producing aninterconnection structure according to claim 1, wherein the secondopening filled with conducting material forms a conductor member, themethod further comprising producing at least one connecting stud on theconductor member.
 7. The method for producing an interconnectionstructure according to claim 1, wherein the second opening is filledwith conducting material forming a conductor member, the method furthercomprising thinning at least one face of the substrate so as to revealone end of the conductor member.
 8. The method for producing aninterconnection structure according to claim 7, further comprisingproducing a conducting stud on the end of the conductor member.
 9. Themethod for producing an interconnection structure according to claim 1,wherein the substrate comprises one or several conducting zones situatedon one of the substrate faces, the formation of the second openingincludes etching from the other of the substrate faces so as to revealat least one of the conducting zones.
 10. The method for producing aninterconnection structure according to claim 1, the simultaneousformation comprising producing one or several other openings situatedinside the closed contour.
 11. The method for producing aninterconnection structure according to claim 1, the simultaneousformation comprising producing at least one other opening forminganother closed contour surrounding the closed contour.
 12. A method forproducing an interconnection structure with at least one via passingthrough a substrate comprising: the simultaneous formation, in thesubstrate, of at least one first opening producing a closed contour andat least one second opening situated inside the closed contour, thefirst opening and the second opening being separated by a zone of thesubstrate, the method further comprising filling the first an secondopening with a conducting material; removing of the material in thefirst opening; and depositing a dielectric material in the firstopening.
 13. The method according to claim 12, wherein the secondopening not passing through the substrate, after being filled with theconducting material, the method further comprising revealing the secondopening to form one interconnection via.
 14. The method for producing aninterconnection structure according to claim 12, wherein afterdepositing of the conducting material in the first opening and thesecond opening, and removing the conducting material from the firstopening, heat treating the interconnection structure so as to form analloy of the material of the substrate and the conducting material. 15.The method according to claim 12, wherein the conducting material isformed in the second opening so as to cover the bottom and the walls ofthe second opening, the method further comprising filling in the rest ofthe second opening with an insulating material.
 16. The method accordingto claim 12, wherein filling in the rest of the second opening with aninsulating material is performed at the same time as depositing thedielectric material in the first opening, the dielectric materialfilling in the rest of the second opening.
 17. The method for producingan interconnection structure according to claim 12, wherein thesubstrate has a base of a given conducting or semi-conducting materialand the conducting material is a metal.
 18. The method for producing aninterconnection structure according to claim 12, wherein the secondopening filled with conducting material forms a conductor member, themethod further comprising producing at least one connecting stud on theconductor member.
 19. The method for producing an interconnectionstructure according to claim 12, wherein the second opening is filledwith conducting material forming a conductor member, the method furthercomprising thinning at least one face of the substrate so as to revealone end of the conductor member.
 20. The method for producing aninterconnection structure according to claim 19, further comprisingproducing a conducting stud on the end of the conductor member.
 21. Themethod for producing an interconnection structure according to claim 12,wherein the substrate comprises one or several conducting zones situatedon one of the substrate faces, and the formation of the second openingincludes etching from the other of its faces so as to reveal at leastone of the conducting zones.
 22. The method for producing aninterconnection structure according to claim 12, wherein thesimultaneous formation comprises the production of one or several otheropenings situated inside the closed contour.
 23. The method forproducing an interconnection structure according to claim 12, whereinthe simultaneous formation comprises producing at least one otheropening forming another closed contour surrounding the closed contour.